Signaling system employing electron beams



Feb. 23, 1954 MQHR 2,670,405

SIGNALING SYSTEM EMPLOYING ELECTRON BEAMS Filed June 10, 1948 4 Sheets-Sheet l INVENTOR MILTON E.MOHR

ATTORNEY Feb. 23, 1954 M. E. MOHR 2,670,405

SIGNALING SYSTEM EMPLOYING ELECTRON BEAMS Filed June 10, 1948 4 Sheets-Sheet 2 INVENTOR MILTON E. MoHR ATTORNEY Feb. 23, 1954 MQHR 2,670,405

I SIGNALING SYSTEM EMPLOYING ELECTRON BEAMS Filed June 10, 1948 4 Sheets-Sheet 3 ,k10 -g 0 0 88888883 0000000000 0000000000 0000000000 0000000000 0000000000 000 0 0 m. J 3

g 0 000 0 0 00000 00 0000000000 0000000000 0000000000 0000000000 0000000000- 0000000000- -0000000 pq 0- 0 1 2 3 4 5 a 7 a 9 OUTPUT 2 x X X x fig: 7. 4 X X 5 4 x x X x x INPUT COMPONENTS INVENTOR MILTON E. MOHR BY WOW ATTO RN EY Patented Feb. 23, 1954 SIGNALING SYSTEM EMPLOYING ELECTRON BEAMS Milton E. Mohr, New Providence, N. J., assignor to Bell Telephone Laboratories, Incorporated, New York, N. Y., a corporation of New York Application June 10, 1948, Serial No. 32,092

8 Claims.

This invention relates to signaling and to apparatus and a method for controlling a beam of charged particles. It is particularly applicable to cathode ray tubes and to systems employing electron beams to repeat signals.

An object of the invention is to repeat signals with the aid of a cathode ray tube.

Another object of the invention is to provide a system having a plurality of input circuits and a corresponding plurality of output circuits, each output circuit being associated with an input circuit, and means for repeating in a selected output circuit a signal applied to its associated input circuit.

Another object is to repeat in a single output circuit a signal appearing in a selected one of a plurality of input circuits. A converse object is to repeat in a selected one of a plurality of output circuits a signal appearing in a single input circuit.

Another object of the present invention is to provide a commutating system for connecting a single signal source to successive output circuits, or for connecting successive signal sources to a single output circuit.

Another object is to control the position of a beam of a cathode ray tube in accordance with one or more variable voltages.

In one embodiment there is provided a cathode ray tube having at least one target divided into separate parts, either one of which may be struck by the cathode ray beam, and means for applying a potential difference between these parts of the target. A feature of thisembodiment is that if the beam is aimed generally toward'a target, the potential difierence between parts of the target itself determines which part of the target is struck by the beam.

The above-mentioned, as well as other objects, together with the many advantages obtainable by the practice of the present invention, will be readily comprehended by persons skilled in the art by reference to the following detailed description taken in connection with the annexed drawings which respectively describe and illustrate a preferred embodiment of the invention, and wherein: r

Fig. 1 is a schematic vertical sectional view taken longitudinally through a cathode ray tube, together with a plurality of signal sources and a corresponding plurality of output circuits respectively associated therewith, the cathode ray tube featuring an array of novel targets and being adapted to repeat in a selected output circuit the signal from its corresponding signal source.

' 2 In the drawing, a portion of the tube intermediate its ends has been broken away.

Fig. 1A is a schematic vertical sectional view taken longitudinally through a portion of a cathode ray tube, featuring a modified target array.

Fig. 2 is a cross-sectional view of the cathode ray tube shown in Fig. 1, certain portions being broken away for clarity of illustration, the position of the section being indicated at 2-2 in that figure.

Fig. 3 is a schematic perspective view of a cathode raytube having a different arrangement of targets, together with certain circuit elements.

Fig. 4 is a schematic elevational view of a portion of the cathode ray tube shown in Fig. 3, looking along the axis of the tube, toward the target array, the shield plate having been removed. The target array is illustrated in connection with a plurality of signal sources and a single output circuit. Such a system may comprise a portion of an electronic directory in an automatic telephone switching system.

Fig. 5 illustrates schematically an arrangement of targets for a cathode ray tube having 1000 targets instead of only 16 targets as schematically shown in Figs. 3 and 4.

Fig. 6 represents a circuit which may comprise a portion of an automatic telephone switching system adapted to produce deflecting voltages which may be applied to deflecting plates of a cathode ray tube having a target arrangement such as that shown in Fig. 5.

Fig. 7 is a diagram to be referred to in explaining the operation of the circuit of Fig. 6.

Fig. 8 is a cross-sectional view of a still different embodiment of a cathode ray tube having targets arranged in a circular formation.

In one embodiment there is provided a cathode ray tube having a plurality of targets each divided into a control anode and an output anode, means for impressing varying potential differences between the control and output anodes of the various targets, and means, such as electrostatic defiecting plates or electromagnetic deflecting means, for directing the beam of the tube generally toward a selected target. The control and output anodes are positioned so that either of them may be struck by the beam when it is directed generally toward the target of which they are a part, the one struck, or the extent to which the beam strikes each, depending upon the potential difference between them. Thus if the beam is directed generally toward a first target, and the control anode of this target is at a considerable positive potential with respect to its output anode, the beam will strike the control anode rather than the output anode. If, however, the control anode is, a moment later, at a more negative potential than the output anode, because, of a signal impressed on the control anode, the heam will shift to thebutput anode. When the beam isst'r'ik'ing the output'anode, this anode will tend to collect electrons, which are allowed to leak on through a load circuit, including a resistor, to ground. If therei rea-si nal such as a series of negative pulses of potential is applied to the control anode, the beam will, at the appearance of each pulse, be shifted to the output anode, thereby producing a negative pulse at the output anode for each one applied at the control anode. This repeating action at a target takes place only when the beam is aimed generally in the directidnofthat target sincethere is, in the absence of the beam, sraaeanynoese'cmve coupling between the'controland outputanode's "of-'ata-rget. Hence when 'th tea sairned -ata second "selected target 'i stead foi at the first, the signal appearin'g'f'at ohtr'ol anode of the second target "will be A tedat the output anode of that target. The maythus'be shifted to select first one tarv nd then another so as 'to cause a signalrepeating action "at the "momentarily selected target. ln sorne special applications of the defvice thebeammaybe swept through such a path "as ct thevari'ous targets in succession.

erence isnow made to Figs. 1 and 2. There is provideda cathode ray tube 26 having beamforining-rrieans '-including 1 a heated cathode-2 i,

an accelerating anode zf whichmay conven- '1'ehly beiground potential, a potential source :23-for maintaining the c'athode at a negative p tial with respect to the accelerating anode, 'andf aigrid 24, biased negatively with respect i to *thcelthode lay a "source -25 of bia's'po'tentiai. The tubeis also provided 'withloeam deflecting 'rneansadapted todiret the'hea'm generally toa desired-target. This beam deflectin means might be termed a'target selector. --In tlie present example such means oomprises a pair of electrostatic deflecting plates 25 connected to a pair of control terminals 27. There may b'e appiisftomeftermllials zi a beam deflecting V6113- ge {or aiming the seam at a selected target.

This-voltage may satisfactorily 'be'halaii'ced to TQ P H It will-beunderstood that for the target selector, instead 'of using electrostatic beam deflecting ans such as the, plates dli, electromagnetic defle tingmeans might be employed.

For convenience in this description, thee rid oi the tube near which the'cathode is located frn'aybe termed the rear end, and the oppc'isite fengroithe tube, toward which the b'eamis 'difirected, may be termed the front orforwar'd end.

The tube is provided, toward its front end, with aflplurality of control or input anodes :36a, 39b, 3Uc,"3i1d and3 lle, and a corresponding plurality output anodes -3l'a,'3lb, tic, 3ld, and 3lefrespectively adjacent to the control anodesjbut f ;s pace 'd therefrom. A control anodasuchas' 32a, fa'hd its associated output anodefsuch as 31 1, may be considered together to comprise a'target.

In the illustrated embodiment the control are generally disc-like in shape, 'with "approximately flat faces presented "to a beam coming from the deflecting plates.

v The output anodes are shown as generally in the shaped flanged sleeves positioned so that the beam may pass longitudinally through them and strike the tor of the associated control-"anode.

control anodes. Each of the output anodes extends rearwardly from its control anode, that is, toward the left thereof in Fig. 1, and is provided toward its rear end with an inwardly extending flange 32a, 32b, 32a. The output anodes also halve-fa portion extending slightly forwardly of the 'control anode, terminating in an inwardly extending flange, 33a, 33b, 336. The flanges Sad-33c overlap somewhat with the control anodes 3Ba-3Be so that if the beam should be in such-a ositiohthat certain of its electrons just miss the edge of a control anode, for example, 3011, they will strikethe flange 33a of the associatedoutputanode. It will be understood that this 'flahgefa'nd'other parts of the output anode,

are electrically insulated from the control anode, so that a potential difference may be impressed between them. The rear flanges 32a-32e toward the left-hand endof the output anodes are provided with central openings Y Ma -3 4e through which the beam may pass.

In case the controlanode 30a is at a negative potential withrespect to its output anode :3la,

the electrons comprising the'beam wilLafterentering the'sleeve-like output anode 3la, tend to the'control anode 33a-is driven'v'ery strongly negative with respectto the output anode-33a,

a portion ofthe beam may tend-actually to reverse in direction, after entering the sleev'e-like output anode, and the flange 32am? the'output anode is helpful in intercepting electronswhich travel along such a reversing path.

The controlanode a, in diverting-the-electrons toward the output anode, ina'y tend to disperse the beam, causing the electrons'to spread apart instead of remaininga beam of small-cross section. Hence the control anodes may in some cases be referred toesheam-dispersingmeans. Itwill benoted thatthe generally'enclos'ed configuration of the output'anode also is 'adapted to provide a-sort of 'shieldingaction, sothat-electrostatic fields generated between-the anodes of one of the targets; do 'not have too-great an effect in other portions of the tube, such as in regions near other targets.

In Figs. 1 and 2, as Well as in Figs. 3,4,5 and 8, yet to be discussed, for simplicityof illustration'the axes of the output anodes have been shown as parallel to the axis of the'tube, and the controlanodeshave' beenshown as lying'in'a plane perpendicular to-the' axis-of the tube. It

will be understood, however, that, particularly if a tube geometry is employed such that the array of targets intercepts a l'arge angle at the deflecting plates, the axes of-the sleeve-like output anodes, instead of being exactly parallelto the axis ofthe' -tube, 'should' eonver'getoward the deflectingplates, in order that the ba'iii may pafss longitudinally through the output anode of the se'lected targ'et and strike approximately the cen- The con- 'trol anodes would each be perpendicular to the axis of its associated output ano'de,-"-and if, as mentioned, the' axes of the output anodes converge toward the defiecting plates, and the control anodes are perpendicular to these axes, respectively, the control anodes may satisfactorily be approximately tangential to a spherical surface centered in a point in the vicinity of the deflecting plates. Such a configuration is schematically illustrated in Fig. l-A. In this figure, deflecting plates are indicated as 26'. The midpoint C of the deflecting plates is the center of a spherical surface P. Control anodes, one of which is indicated as 30a, are tangential to this surface and sleeve-like output anodes, one of which is indicated as 3| a, are arranged with their axes converging at the point C.

Referring again to Figs. 1 and 2, there is provided, just to the rear of the targets, that is, between the targets and the cathode, near the targets, a shield 35 of electrically conducting material, provided with openings 36a36e, positioned to coincide generally with the openings 34a-34e in the rear flanges of the output targets. The purpose of the shield 35 is to prevent variations in potentials of various targets from affecting the beam significantly during its transit through the tube before it reaches the region of the tarets.

In the embodiment shown in Fig. 1, each of the output anodes, 3la--3le, is provided with an output circuit including a load resistor, 3'la-3'Ie, respectively, connected between the output anode and ground. The ungrounded ends of the load resistors 31a31e are connected to a series of output t e rminals, 38a-38e, respectively.

A plurality of signal sources 39a39e are respectively connected to the control anodes 3lla 30c and to the negative terminal of an adjustable source 40 of direct current bias potential, the positive terminal of which is grounded.

Thus the signals from the sources 39a-39e are applied in series with the bias voltage from the direct current source 40. The source 40 may, in some modes of operation, be adjusted to maintain the control anodes at a sufficiently negative potential that when the value of the signal applied is zero, a portion of the beam will strike the output anode of the selected target and a portion will strike the control anode. When the control anode is driven to a more negative potential, a larger proportion of the beam will strike the output anode. When the signal from the source is a small positive one, the control anode assumes a less negative potential, and a smaller proportion of the beam will strike the output anode, a greater proportion striking the control cally all the beam will strike the output anode.

The reason for employing the bias source 40, in embodiments in which it is employed, is that without this bias practically none of the beam would strike the output anode when the signal is zero, and therefore a positive portion of a signal, elevating the potential of the control anode with respect to the output anode, would produce the same response at the output anode as would be produced by zero signal. Consequently, in the absence of a bias, there may be a sort of rectifying action, in which the positive portion of the applied signal is clipped.

In certain cases, the bias may satisfactorily be omitted. For example, a series of negative-pulses having steep leading and trailing edges may satisfactorilywbe repeated without .the use of bias,

particularly if it is the spacing of the pulses which is important, rather than their amplitude. In the absence of a pulse, none of the beam will reach the output anode, but during a negative pulse all the beam will be directed to the output anode.

The device shown in Figs. 1 and 2 may be operated as follows. It may be assumed that it is desired to apply to a selected output terminal, such as- 38a, the signal supplied by its associated signal source 39a. This signal may, for example, comprise a series of voltage pulses. For the sake of the present illustration it will be assumed that the signal is of the pulse-position-modulation type, sometimes referred to as of the pulsetime-modulation type, in which there is periodically transmitted a reference pulse and a second pulse delayed by a variable interval from the reference pulse. It may be assumed that the pulses applied to the control anodes are of negative polarity. It may further be assumed that the pulses are of sufficient amplitude to shift the beam substantially from the control anode to the output anode. A zero bias maybe used.

A direct current voltage is applied to the defiecting plates 25 through terminals 21, of proper magnitude and polarity to direct the beam toward the target to which the selected output terminal is connected, in the present example, toward the target comprising the control anode 30a and the output anode 3111. During moments when the signal is positive the beam will strike the control anode 30a and virtually none of the beam will strike the output anode 3la. During moments when a negative pulse is impressed on the control anode 30a, virtually all of the beam will be caused to strike the output anode 31a because this anode will be more positive than the control anode. Thus if the signal applied to the anode 30a comprises a voltage which is normally slightly positive, and includes a series of negative pulses, the beam will normally be attracted to the control anode and will be caused intermittently to' swing over to the output anode 3m. During the moment when the beam is striking this output anode, the electron beam will cause negative charge to collect on the output anode, thereby causing a fiow of electrons through the load resistor 31a. As a result of the intermittent current pulses through the load resistor as the beam swings to and away from the output anode 3la, there will appear at the output terminal 38a a series of negative voltage pulses, thereby repeating the signal applied by the signal source 39a. It will thus be seen that by aiming the beam generally toward a selected target it is possible to apply to a selected output terminal a signal corresponding to that supplied by its associated signal source.

It will be noted that in the illustrated embodiment the output anode and the control anode which together comprise a target are so positioned that the beam may strike either of these anodes, depending upon the potential difference between them. This arrangement is to be distinguished from an arrangement in which the means which deflect the beam are entirely separate from the target, and are themselves not struck by the beam.

Another feature to be noted is that in the illustrated embodiments the control anodes are actually farther from the cathode than are the output anodes. Stated differently, there is provided a cathode ray tube comprising a source of a beam of electrons, an output anode, andan control anodes beingdeshgnatedby the reference numerals. ita;, ifib 56c fil ip endmhe oot put. anodes being-designated by the,refersnce. numeralslila ilh ilo, fll'p anodesurep re sented by referencenurne als haying like sube; scripts. being associated. together to comprise ;a.. target, That is, control anode. .d-Smand routput anode Ala. togethe z iorm target; controlanode 466 and outpuhanode. 41b, form another, target, and. so on. Preferablythe targets. are arranged with the axes of the output, ,anodesconverging: in

the direction from .whichthe.beamtccmesuso as to receive the beam-morereawy, aszwa .previ ously explained. in. connection ,withfig, 1 A,

Each of the ,targetsuisv proyided with an input circuit including. a 7 source of si nals. Signal. sources, 48a-48p-,;;are.,connected to the control anodes lite-43p, respectively.

There-is providecl a;- beam. deflector adapted to aim the beam. generallytoward any, selected. v target. This, beam defiectmh ziraabomprise a pair. of horizontal platesig angl -56 for. controlling the 7 vertical. position ,of thebeam, and a.pair. .oi ver: tical plates 5l and ,52;for controlling the hori.. zontal position. of the beann Theplatesfiiland. 52 may be maintainedfat constantdirect current. potentials ,during... operation of the; device, and hence-the position oi thebfiam. may ,be controlled by applying controlpotentials to the .plates., 4fl and 51. through-terminals .53 and 55, whichare respectively. connected. to the plates 49 and 51. through leads, 55 and .56. For. applying ,constant potentialstq the platesfifliand 5 2 there maybe. provided, adjustablebias sources. 5.? and 5Brespectively, having one terminal grounded and the otherterminal connected to the deflecting, plates Thus theseibias sources may conveniently bea rangedto'apply to the. plates 59 and 52 positive: potentialsof such? value that .Whenthe plates Q5. and 5| areat ground or some other reference po tential, the beamwill rest on the upper lefthand target comprisingthe anodesfifi andgiia.

Itwill be understood thatinstead. oi the. ,ar-,. rangement shown, the circuit may be arranged so that the deflecting yoltages for. both the horizontal and vertical plates may be balanced to groun Just to the rear of the targets, thereisprovidecl.

a shield. 59. If the targets are-locatedarounda sphericalsurface the general ..,arrangement own i g! l,A .-th,e h eldi p efe ablr pherical and concentric' with, the first-mentioned sphericalsurface, r

The output anodes are in the embodiment at 11 E s- =4. neet dv o a eemma 9. m. 6 bettveen-. -t hich;point and groundthere. is connected-a loadresistorfi I-.

It maytherefore he seenthat lithe beam is, aimedzgenerally. in .the adirectionzof. Jone ,=of.1t111 "targets; therelwillberepeatedatiheapointzlilhthe. 7-5

si nal jromsthe so rcescjnnected to hei mi rol.

he s wt ta eet If .-5@ hu.l$ =b iacr ssthetargde in succession, then th system described. thus far would be in the nature of a .commutator,.. serving to apply to the common: -.output point-Qt 0 signals fromsuccessiveisoiu'ces Mid-T4 810,,

it is desired to obtai certaininformation ree garding the line .of the called subscriben suoh .as whether.thisiline is busy, .or .to ,obtain cer-.. tain v ir formation- .from,. one or ,mQretrunKS, ,D'ee pending upon -,the, information qbtained, certain, switching operationsiwill thereafter be performed;

In using the-cathode ray-tube of, the typeshowm in Figsuilhand 4 .insuch a switching systemhthe. signal sources 48015-5182). may-representQthe.svarie..

oustrunkswor lines to be .called, connected..to

flve s o m eno flfi mtfia...andthere may, be available. fr mpthese lines signals, of

practically any type, such as FM, AM, pulse time modulation, and the like, corresponding to the informatioridesired. There may-be .provide;1,.asende1'.62','oneof.the generalpurposes of which is to oinyestigatea desired lineand toperiorm. switching operations depending upon. informer.

ticn received .iromffih it. line. the present. system the sender 82' is connected ,Jcy leads 6,3

and 641 tothe terminals 53 andj l which. conl. e. o itionof t e. b mpf. he h'oderay. t e 4 n i ada ted to a plrt th se. ten n ls su h. a combination. of d c u ren otentials va s flwillpoint the beamat the targetto which'the desired line is connected, The common pu m t fo et rsets is conn c ed y a" e d- 5 tot e r .2;. for re u ninethe. ired i ormat n t hese de To determine the line calledbythe senden r pr vid o r l, m ans. 6 whi h; m y.

te m d. aj e d rw nt ql en. Q ectedto the;

e der 6.2 by d .5 nd 68- e 'senderec ne l y co rise a pa at s .respon ive q si nals.

m a l ng, c bers. st ion or t o e nt o e ne .ada ted-t a set ese d to callapan marl ne- T d s tro le n: p essa trq p en alsw o e se ...t 0 sh h leads fil and 63,. and respgnse thereto the ndereppl s u ble. ontrolpo a sto h terminalsjiii" and 5 4' to ppint the beam at. the t rse ,..tc w i h ..ca l dl e.. connected.,.

. i q ro e rip iomit may b assumed. t t. ai esteur n o t ol potent a w t re: speptto r und. applied. by he .sende rc r. troller iit through the lead 61 to the .senderj;

an is merely e e ted b the en ena d ap i as a control potential of the same value through th j e d. .63 t t e te mina 5 1' i-contro ns. the vertical position of the ,b eam.,

It may likewise be assumed that aydirect cur-e rent control potential isapplied through-the lead 68 to the sender -62 and is-repeated by the-sender; being applied as acontrol potential of the same m lto the-terminal 54 through the lead, for controlling;the-horizontal.1position'of the beam.

As will be explained,.inorder to produce-asuih. able potential; at, ;for;example.w the. lead .61, ior: controlling the vertical positionioi..theqbeamthe sendenecontroller :56; is; w in one embodiment, provided-iwithaai series of potential :sources. of differentsvalueal. an;.-adding :circuit,: a seriesof.

switches rotor applyingizselectewieombinationssof..

' number of targets may be desirable.

' tical spacing.

a distance 28 downwardly.

9 potentials from said sources to said adding circuit for producing a sum potential which appears at the lead 61, and means for selectively actuating one or more of said switches to produce a sum potential of the desired value. For producing the control potential'at the lead 68, in order to control the horizontal position of the beam, there is provided another adding circuit, together with an associated series of potential sources, a series of switches, and means for selectively actuating the switches. The means for selectively actuating the switches may, for example, comprise a series of relays. Suitable means are provided for energizing combinations of these relays in accordance with the line called. Thus for example when the subscriber dials a particular number, his instrument may transmit a series of voltage pulses, which by suitable means may be caused to energize a corresponding combination of relays. Such last-mentioned means will be understood by those skilled in the art, and therefore need not be described in detail. In the subsequent description of the sendercontroller, only the relays and the elements responsive thereto will be discussed in detail, since it will be assumed that suitable means for energizing combinations of these relays are provided,

either as a part of the sender-controller, or as a part of means for controlling same.

If a cathode ray tube of the general type shown in Figs. 3 and 4 is to be used as a portion of an automatic telephone switching system, a large Thus instead of employing 16 targets as shown in Figs. 3 and there may be employed, say, 1000 targets, arranged in a matrix, as is schematically illustrated in Fig. 5. It will be understood that the array in Fig. 5 comprises a matrix arrangement having 100 horizontal rows of targets and 10 vertical columns.

Fig. 6 may now be referred to for description of circuit means which may comprise a part of the sender-controller 66, adapted to produce in the leads 6! and 68 a pair of direct current control voltages which, when repeated by the sender 62 and applied to the horizontal and vertical deflecting plates, respectively, of a cathode ray tube having an array of targets such as that shown in Fig. 5, will point the beam at a selected target.

It may be assumed that bias voltages are applied to the deflecting plates and 52 respectively by the sources 51 and 58, of such value as normally to position the beam on the target in the extreme upper left-hand corner of the array, when the potentials applied to the plates 49 and 5| are each zero or'some other reference potential corresponding to a normal or undeflected condition. It may be assumed in the illustrated embodiment that the targets are uniformly spaced throughout a given row or column, and that the horizontal spacing is equal to the ver- If the center-to-center separation of the targets in the horizontal direction and also in the vertical direction is represented by the symbol S, then to move the beam from its normal position, on the upper left-hand target, to, say, the target T in the fourth vertical colum and the third horizontal row, it is necessary to shift the beam a distance 3S to the right and The voltage increment in the lead 61 to produce a vertical displacement of S or in the lead B8 to produce a horizontal displacement of S may be represented by the'symbol V, and it may be seen that to shift thebeam from its normal position to the target T, there should be produced a voltage increment of 2 v. in the lead 61 and a voltage increment of 3 v. in the lead 68. In order to deflect the beam to the right and downwardly, these potential changes should be in the positive direction, assuming that there is no reversal of polarity within the sender 52 between the lead 61 and the lead 63, or between the lead 68 and the lead 64.

As shown in Fig. 6, in order to produce in the leads B1 and 68 control potentials of the desired values, there is provided, for each of the leads, a series of potential sources of difierent values, an adding circuit having an input terminal for each of said potential sources and an output terminal, and means for selectively connecting one or more of said potential sources to said adding circuit to produce at said output terminal a resulting or sum potential. The sum potential is controllable in steps, depending upon the combination of potential sources connected to the adding circuit.

Adding circuit for producing vertical deflection of beam The output terminal of the adding circuit associated with the lead 61 may be considered to be a point 69, which is coupled to the lead 61 by direct current responsive circuit means comprising a. potentiometer 1c and an amplifier II. Potential changes in the lead 61 will be proportional to potential changes at the point 69 but in the opposite direction, assuming that the amplifier H comprises one stage. That is, a decrease in potential at the point 69 will produce a proportionate increase in the potential of the lead 61. The proportionality factor may be initially adjusted by adjustment of the potentiometer 10. During actual operation of the device, no further adjustment of this potentiometer is necessary.

For the lead 6'! there is provided a first group of four potential sources 15, 16, I1 and 18, having values of 1, 2, 4 and 5 volts respectively, and-a second group of four potential sources, 19, 80, 8| and 82, having values of 10, 20, 40 and 50 volts, respectively. With the arrangement shown,'these potential sources should have their positive terminals grounded and their negative terminals adapted to be connected to the adding circuit to be described. It will be understood that while the potential sources 15-82 need not necessarily have the exact values given, they should have values proportional to the values given. The adding circuit for the lead 61 comprises eight equal resistors 8390, inclusive, one end of each of said resistors being connected to the common output. point 65, the other or input ends of the resistors being respectively connected to the contact arms of a series of relays Hill-401, adapted, when energized, to connect the resistors 8390 to the respective potential sources 75-82. When not energized, these relays are adapted to ground the input ends of the respective resistors 8390. 1 The adding circuit including the resistors 83-90 together with the associated potential sources and relays, is adapted to produce at the output terminal 69 of the adding circuit a negative potential proportional to the sum of the various potentials applied to its input terminals. This sum may be any number from 0 to 99, inclusive, depending upon which of the relays 15-432, or combinations of same, are actuated. There consequently may be produced in the lead $7 a voltage increment. of nV, where n is any to deflect the *beam from one target to the next. The principles. of operation'of'the adding circuit described will be understood by those skilled in the art, and need not be'discussed in "detail. 'It will suffice to illustrate withone or two specific "in the leadBl a'voltage increment of 8 v., the re- ";lays 15, 'Idand I8 will'be energized, connecting 'ithe 1-, Z-and 5-vo1t potential sources to their associated resistors.

Reference ismade to Fig. '7. This diagram illustrates different combinations of sources 55-48 of potential which should be applied to the input ends of the resistors 'of the adding circuit of Fig. S'in'order to produce a desired potential.

Shown vertically along the left-hand side of the diagram are .thevoltages; or relative" potentials, of input potentia-lsources; such as 'I5'I8. Shown horizontally along the top of the diagram,..on a

dimensionless scale, are thepotentials which'it is desired to'derive. "The potentialappearing at the 'pointfifi as a result. of'connecting combinations of the sources I5"I8 to theadding'circuit will be proportional: to the'numbers'along the top of the diagram 'iniFig. Land theincreinent in the" potential in lead T61 will be V multiplied'by the number indicated in this scale. The X marks shown under thevarious numeralsat the top indicate the combinations of input sources "which should be connected to the adding circuit in order .to obtain the potential increment in lqllBSfiOIl.

Thus, for example;.under 8,'which.indicates a potential incrementof 8 v.in the-lead 61, thereiare X marks indicating "that the l=volt, 2-'volt,:;a'nd

'5-voltpotential sources should be connected to the adding'circuit. "'The'diagram inFig. 7-.will

. indicateother' combinations necessary in order to obtain avoltage .increment'of from" zero to'9'v.

" The potential sources 19', 80',8l and 82, having values of 10, 20; '40 and '50 v.volts, when J used in combination with the. potential: sources ":16, make it possible to'obtainan increment ofirom zero to 99 v. in the lead 61.

1 *Adding circuit for producing horizontal xd'efleciion o beam "The output terminal of the adding circuitassociated with the lea'df68 may be considered to be a point I 08 which is coupled -to the lead'liB; by

direct current responsive circuits means comprising a potentiometer I09 and an amplifier I I0.

Potential changes in the lead 58 will be .pro-

:portional-topotentials at the point I08 but in the -,opposite direction, assuming that the am- "plifier IHJ comprises one stage. 'That is, a decrease in potentialat the point108'will produce a proportionate increasein the potential of the J lead 168. "Theproportionality factor may be (initially adjusted by adjustment of the potentivolts, respectively, andan adding circuit comprises four'equal resistors H9, I20, I2I.and"'I22. One-end o'f each of "thBSB'TTESiStOIS is' connected to the common output point I 08, "the other" or inputends-of the=resistors being respectively connected-td the-=cdntact arms 'of a series iof r'elays to connect-the input= ends of the resistors"! I 9- I 22 to the' respective potential'sources H5l-l8.

5 When not energized; these 'relaysare adapted to ground thednputchdsof these resistors.

The operation of thea'dding circuit for the 1ead'- 68,'--together =with its associated relays and -potentialsources, isgener'ally similar to the op- 10 eration of- -the 'adding'circuit associated-with the-lead 61; except *that potential changes of from zero to 9 v.-may be pr'oduced in the lead fifi, -while'-potential changes of from =zero to '99 v. may

'be produced irr the'le'ad '61 *As has previously been stated,- the potential of the lead B'icontrols the-downward or vertical defle'ctionpf the beam, and the potential-0f the lead '68 controls the-deflection-of the beam toward the-right;- horizontally. With an-arrayof targets such-asthat shown in Fig. 5, having 10 *vertical columns and "100 -horizontal rows, in

order to position 'thebeam on any ot the i000 targets, *itis=-necessary to be able "to apply "to thelead fit a-"v'oltage increment of from zero to 9 v., and-to -be ab1e"-t0app1y to the-lead 61 a voltage'increment of fromzero to '99 v. It may *be seen -from the-previous description of 1 the circuit elements-" of Fign6fthat such a system is capable of positioning the -beanr 'onany of the 101000 -targets, -since 'it-iscapable -of applying *such'increments to-theleads B1 and B8.

The 1000- targets of Figfi'may -be considered to correspond to leoo' lines' which 'it may be desired to-call. when a calling subscriber --calls a 'de sired line; a selectedrcombination =of the relays shown in Fig 6 will be energized; by means I not i shownfthereby causing the-' beam to be pointed at the targ'et corre'sp oriizling toithe desired *line. "Information' froni that iine will then-be repeated 40 at the point 60 of Fig. 4, and fed back through the lead- 65"to the sender 'B2 The sender -will thereaiter perform:any necessary :s'witching op- 'erations.

The usefuln'ess of the device- 0f the present invention as a -comniutator has heretofore been described. In such anapplicatiomit may-be desired to-sweep the beamcontinuously'over suc- --cessive targets. -'-A -'targ'et arrangement: which is advantageous for"such 'an application is shown in' Fig. '8. Ir-1" this arrangement the targets I39 are disposed in: a -circular: array, conveniently -concentric'-"with the axis ot a: cathodecraystube 3 I ,:and the beam may-be givena; circular scan- -ning motion;"'thereby 'causing it to sweep over successive targets. Onezadvantage of: such'ian "array is "that the beam' may move atiuniform speed and will sweep oversuccessive ritargets iat uniform-intervals; -as i distinguishedi from :an tarrangement in which the-targets ares inrone or i more strai'ghtlines; in which .case' -thetbeamimust "perform-a recovery motion atraa'vveryi rapidzrate, if the targets "are :to -be swept overeat 'iuniform "intervals.

Itwill be' understood that therefihas abeemdisclosed" herein novel: method @aswvell zas: :novel apparatus. Thus; for examplemthere; has'zbeen disclosed a method ofi repeatinga; signalrpotential with the aid: of an: electron ibeam compris- "ing directing said beam-ia of: electrons toward a control electrode, applying isaidgsignal :potential to Lsaid control electrodeita :disperse': said beam and to deiiectsaid electronszamayrimnr saidmlccstrode tc extents;instantaneouslyafdetermined byithe amplitude 'andipolar itysof gsa'id-esi nal; and "collecting thev electronstzdeflectednby .isaid ,i'filefi- 13 trode. In some embodiments, the signal potential applied to the electrode maybe sufliciently negative at times that the electrons are driven not only outwardly from the axis of the beam but generally backwardly toward the source of i tively aiming the beam at one of a plurality of zones, applying to said plurality of zones, respectively, time-varying signal potentials suflieciently negative at moments to repel electrons of said beam from said zones, and collecting the repelled electrons.

Where the present specification and claims refer to methods and apparatus for repeating signals, it will be understood that it is intended to include not only repeating systems in which the output signal is a faithful reproduction of the input signal, but systems in which the output signal is determined by, but is not exactly proportional to, the input signal.

The teachings of the present invention are applicable not only to beams of electrons, but to beams of other types of charged particles.

While a suitable form of apparatus and mode of procedure, to be used in accordance with the invention, have been described in some detail, and

certain modifications have been suggested, it will be understood that numerous changes may be made without departing from the general principles and scope of the invention.

What is claimed is:

1. In a cathode ray tube having beam forming and directing means, a plurality of pairs of anodes, one anode of each pair being a sleevelike output anode and the other being a control anode located at the far end and within the output anode of the pair, said pairs of anodes being positioned so that the beam may be directed lengthwise through any one of said output anodes toward the control anode therein, and means including connections individual to each said pair of anodes for applying a difference of potential between the anodes of the pair to cause the beam to strike a selected one of said pair of anodes.

2. A cathode ray tube commutator comprising a plurality of targets, each divided into separate anodes, a plurality of input circuits respectively connected to one anode of each target, a plurality of output circuits respectively connected to another anode of each target, deflecting means adapted to point the beam of the tube toward successive targets, and means for applying a plurality of signals to said respective input circuits. 3. A signaling system comprising input circuit means, output circuit means, control circuit means, and a cathode beam tube comprising a plurality of pairs of anodes, one anode of each of said pairs being connected to said input circuit means, the other anode of each of said pairs being connected to said output circuit means, and beam forming and deflecting means responsive to said control circuit means adapted to direct the beam toward a selected pair of said anodes, the anodes of each pair being positioned so that said beam may strike either anode depending upon their relative electrical potentials, said control circuit means comprising connections for a series of potential sources of'different' values,

an adding circuit, a series of switches for applying selected combinations of potentials from said sources to said adding circuit for producing a sum potential, connections for applying said sum potential to said beam-deflecting means, and means for selectively actuating one or more of said switches, to apply such a sum potential to said beam deflecting means as to aim said beam at a selected pair of anodes.

4. In an automatic telephone switching system, a cathode ray tube having beam-producing means, a plurality of targets each divided into a control anode and an output anode, deflecting means adapted to direct the beam generally toward a selected target, a plurality of circuits respectively connected to said control anodes and adapted to apply thereto signal potentials to shift the beam from one of said anodes of the selected target to the other, thereby repeating at the ouput anode of the selected target the signal applied to its control anode, a plurality of switches, means for actuating a selected combination of said switches corresponding to a particular circuit which it is desired to call, and means responsive to said switches adapted to cause said deflecting means to direct said beam generally toward a selected target.

5. In a telephone exchange system, a cathode ray tube having beam-producing means, a plurality of targets each divided into a control anode and an output anode, deflecting means adapted to direct the beam generally toward a selected target, a plurality of lines respectively connected to said control anodes and adapted to apply thereto signal potentials to shift the beam from one of said anodes of the selected target to the other, thereby repeating at the output anode of the selected target the signal applied to its control anode, a sender adapted to cause said defleeting means to direct said beam generally toward a selected target corresponding to a line from which information is desired, and circuit means connecting said output anodes to said sender.

6. In combination, means for propelling a beam of charged particles passing through an aiming zone, an aimer adapted to impress a field on said zone to aim said beam along a selected one of several diverging paths, several output electrodes each having a portion parallel to and surrounding one of said paths, a repeller electrode within each of said output electrodes biased relative to its output electrode with the same polarity as the charge on said particles, and means for individually applying signal potentials to said repeller electrodes relative to their output electrodes.

'7. A method of repeating signals involving the use of an electron beam and an electrode, said method comprising directing said beam of electrons toward said electrode, applying to said electrode a varying input signal potential sufiiciently negative at times to disperse said beam and to repel said electrons from said electrode with a component of movement in a direction the reverse of that of said beam, collecting said repelled electrons, thereby accumulating a charge dependent upon variations in said signal potential, and continuously discharging said collected electrons to derive an output signal potential dependent upon said input signal potential.

8.111 a communication system including a plurality of circuits which may be called, each of said circuits being identified by a plurality of referenceecharacters emethodzofsselectivelw er .peating at'.--a.n; :ontimt:pointl a; signalpotential appearingin -.a=-. ca1-1edcircuit, 5comprisingxapplyingsignal potentialse-fromnsaid; circuits:to-- a -plurality 10f correspondingoontrolzones; respectively;

adding. a combination of potentials individually corresponding to the reference. characters of; 8.

deflectingpfield-to aim saidbeam. of-- electrons toward the -.control. zone to which the :signal potential of saicl called -.-circuit-: is applied, said;z signal potentials; being;- at? times suificiently. negative to .repel said electrons from said 1 last-mentioned zone; collecting: =said.;repel1ed electrons, thereby derivingan output signal; and-applying said I output -signalto saideoutputv point;

- MILTQNEE. IVIOI-IR.

UNITED STATES RATENTS Number Name Date Bowie Sept. 5, 1939 Bruche Sept. 12, 1939 skellett June 11, 1940 Morton 2 Aug. 27,1940 Hanscom Dec. 10, 1940 Gray July 29, 1941 Goldstine July 21, 1942 Renshaw Nov. 10, 1942 Hadekel Oct. 31,1944 Espenshied; June, 26, 1945 Skellett Feb. 19,1946 Kilgore June 11, 1946 Tunick. Aug. 12, 1947 Sears Oct. 26, 1948 fRansom ..7 Mar. 1,,1949 Rosen July 26, 1949 Rusterholz Sept. 5,1950 

